trust

Tie the end of a string to a small weight. Throw the weight over a limb or the top of a swing set. Remove the small weight and replace it with a larger one such as a baseball or a stone. You might use tape to help hold the string to the weight. Tie the other end of the string to something so the weight is hanging about a foot off the ground. Pull the weight to the side as if to start the weight swinging when it is released. When the weight is as high as your face prepare to release it. The weight should be about 2 inches from your face when you let go of it. Be sure that you do not push the weight away as you let go. Be sure that you do not move your face toward the weight after you let go. Release the weight. It will swing away from you and then toward you. As it is coming toward your face trust the laws of physics which say that the weight will stop before it hits your face. When the weight is released, the force of gravity causes the weight to move. Energy is added to the weight as it moves closer to the ground. Gravity takes away the same amount of energy when the weight moves away from the ground. When the weight gets back to the point at which it was released, all the energy that gravity added has been taken back. To keep from getting hurt make sure the string or rope is plenty strong enough. Whatever holds the string should not move at all. The string should be securely attached to the weight. This demo was done with a bowling ball on the tv program 'Bill Nye the Science Guy'. I was impressed.